Regulation of sororin by Cdk1-mediated phosphorylation
Regulation of sororin by Cdk1-mediated phosphorylation
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DOI：
10.1242/jcs.085431
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发表时间：
2011-09-01
影响因子：
4
通讯作者：
Taylor, William R.
中科院分区：
文献类型：
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作者：
Dreier, Megan R.;Bekier, Michael E., II;Taylor, William R.
肿瘤细胞通常是非整倍体，这是一种导致癌症进展和耐药性的条件。了解染色单体是如何在适当的时间连接和分离的，将有助于揭示非整倍体的基础，并将有助于揭示肿瘤细胞的行为。姐妹染色单体的凝聚力由多蛋白复合体粘附素维持，粘附素由Smc1、Smc3、Scc1和Scc3组成。Sororin与粘附素复合体相关，并调节姐妹染色单体的分离。索洛林在有丝分裂中是磷酸化的；然而，这种修饰的作用尚不清楚。在这里，我们发现潜在的细胞周期蛋白依赖性激酶1(CDK1)磷酸化位点的突变使得索洛林在整个有丝分裂过程中都滞留在染色体上并与粘附素结合。用DNA-纤维素可以从细胞裂解物中沉淀出索洛林，只有低磷酸化形式的索洛林显示出这种联系。这些结果表明，在有丝分裂中，索洛林的磷酸化导致其从染色质中释放出来。此外，索洛林的低磷酸化形式增加了姐妹染色单体之间的凝聚力，这表明CDK1对索洛林的磷酸化影响了姊妹染色单体的凝聚力。最后，磷酸化缺陷的索洛林可以减轻内源性索洛林被敲除后发生的有丝分裂障碍。这种有丝分裂阻断被Aurora激酶抑制剂ZM447439取消，这表明过早分离的姐妹染色单体通过Aurora激酶依赖的途径激活纺锤体组装检查点。
Tumor cells are commonly aneuploid, a condition contributing to cancer progression and drug resistance. Understanding how chromatids are linked and separated at the appropriate time will help uncover the basis of aneuploidy and will shed light on the behavior of tumor cells. Cohesion of sister chromatids is maintained by the multi-protein complex cohesin, consisting of Smc1, Smc3, Scc1 and Scc3. Sororin associates with the cohesin complex and regulates the segregation of sister chromatids. Sororin is phosphorylated in mitosis; however, the role of this modification is unclear. Here we show that mutation of potential cyclin-dependent kinase 1 (Cdk1) phosphorylation sites leaves sororin stranded on chromosomes and bound to cohesin throughout mitosis. Sororin can be precipitated from cell lysates with DNA-cellulose, and only the hypophosphorylated form of sororin shows this association. These results suggest that phosphorylation of sororin causes its release from chromatin in mitosis. Also, the hypophosphorylated form of sororin increases cohesion between sister chromatids, suggesting that phosphorylation of sororin by Cdk1 influences sister chromatid cohesion. Finally, phosphorylation-deficient sororin can alleviate the mitotic block that occurs upon knockdown of endogenous sororin. This mitotic block is abolished by ZM447439, an Aurora kinase inhibitor, suggesting that prematurely separated sister chromatids activate the spindle assembly checkpoint through an Aurora kinase-dependent pathway.